<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>

<body>
  <script>
    var obj = {
      id: 12,
      uname: 'wjn',
      age: 28,
      pname: '大米',
      price: '1999',
      now: '999'
    }

    function fn(x, y) {
     
      return  x + y
    }
   console.log(fn(1)) //NaN
  //  console.log(undefined+444)
  </script>
</body>

</html>